Wow! You really put that stone to good use. Those are sweet!
The non-heat treated grey stuff is quarried Georgetown flint and was pulled out from deep deposits. It has a different workability than the surface-collected flint (the quarried is much easier to pressure flake). The heat-treated stuff is shinier than the raw.
Yeah the grey stuff pressure flakes like a dream ! That stuff isn't heat treated? I would not have guessed that. The brown type that looks like it comes from cobbles I would assume is heat treated. I have tried some of that cobble that I know wasn't heat treated and it was harder than my pecker in the morning!
The brown rock reminds me of some rock we have in Tampa Bay called ledge (fossilized algae) I broke a couple bifaces it seemed susceptible to shock more than the grey stuff.
Well, they both were a pleasure to work much appreciated !